Connector component for optical fiber, manufacturing method thereof and optical member

ABSTRACT

A connector component for optical fibers has good dimensional accuracy and parallelism. The connector component includes a base material. The base material is provided with at least two holes for inserting and fixing optical fibers therein. The base material is made of quartz glass. Inner components are arranged for forming holes for inserting optical fibers in a die for forming an outer form of the connector component with a dimensional accuracy equal to or less than 2 μm. Slurry is poured into the die, the slurry including quartz powder, a resin binder, a dispersant, water and a curing agent. The poured slurry is cured and heated under vacuum so as to vitrify the cured slurry to obtain the quartz glass.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a connector component foroptical fibers, a manufacturing method therefor and an optical memberfor arranging optical fibers with good dimensional accuracy and goodparallelism in a connector component for connecting optical fibers andin an optical communication device such as an isolator, a circulator, asplitter, a light guide, a thermochemical switch and an optical switchused in the optical communication field.

[0003] 2. Description of the Related Art

[0004] In the optical communication field, a connector component foroptical fibers such as a single-core ferrule or a two-core ferrule usingzirconia ceramics or glass-ceramic, and a fiber array as shown in FIG. 1in which V-shaped grooves are formed on a board made of glass-ceramic,quartz glass, and silicon are used for setting the optical axis in aconnector for connecting optical fibers, an isolator and a circulator,or a ferrule and a fiber array for optical fibers used for connecting toan AWG waveguide.

[0005] However, in the connector component for optical fibers such as aferrule for optical communication and a fiber array, when the materialof the ferrule and the fiber array is zirconia ceramics, in a case wherethe ferrule and fiber array are mechanically stressed, the crystalstructure of ceramics is transformed from tetragonal crystal tomonoclinic crystal. The phase change causes an increase in the size ofthe ceramics. Thus, the distance between holes of the ferrule and thedistance between the V-shaped grooves of a V-shaped groove type fiberarray change. Accordingly, a high-accuracy optical connection cannot bemaintained for the long term.

[0006] Additionally, when the material of the ferrule or the fiber arrayis different from the material of the optical fibers, the thermalexpansion coefficient of the ferrule or the fiber array differs from thethermal expansion coefficient of the optical fibers. Therefore, the sizeof the ferrule or fiber array and the size of the optical fibers varydifferently according to the environmental temperature. Thus, bondingsurfaces of the ferrule or fiber array and the optical fibers arestressed. At the same time, there is a possibility that adhesionstrength is deteriorated. Accordingly, such a connector component foroptical fibers is not reliable. Further, when using the V-shaped groovetype fiber array, two to three boards made of quartz are combined so asto fix optical fibers. Thus, more manufacturing processes are required.Additionally, since two to three kinds of costly adhesives are used, theassembling is complex and the cost increases. As a result, diffusion ofoptical communication is prevented.

SUMMARY OF THE INVENTION

[0007] It is a general object of the present invention to provide animproved and useful connector component for optical fibers,manufacturing method therefor and an optical member in which theabove-mentioned problems are eliminated.

[0008] A more specific object of the present invention is to provide aconnector component for optical fibers, manufacturing method thereforand an optical member that can arrange optical fibers with gooddimensional accuracy and good parallelism.

[0009] In order to achieve the above-mentioned object, according to oneaspect of the present invention, there is provided a connector componentfor optical fibers, the connector component including a base materialprovided with at least two holes for inserting and fixing optical fiberstherein, wherein the base material is made of quartz glass (fused silicaglass).

[0010] According to the above-mentioned aspect of the present invention,both optical fibers and the base material of the connector component foroptical fibers (referred to as “connector component”, hereinafter) aremade of quartz glass. Quartz glass has a small thermal expansioncoefficient. Thus, matching of thermal expansion coefficients of theoptical fibers and the base material is improved. Accordingly, adhesionof the optical fibers and the connector component, such as a ferrule ora fiber array, becomes more reliable. Additionally, compared withV-shaped grooves, surface treatment of bonding surfaces is easier andthe process for polishing, for example, is better. Further, theconnector component is provided with two or more holes for inserting theoptical fibers such that the holes are arranged with a predetermineddistance there between. Therefore, by using the ferrule or the fiberarray structured by a single component, it is possible to arrange andfix a plurality of optical fibers with high accuracy. The holes in theconnector component for optical fibers may be arranged in not only asingle line but also in a plurality of lines. For example, 8 rows×1line, 12 rows×1 line, 40 rows×1 line, 2 rows×2 lines, 4 rows×2 lines, 4rows×4 lines, 8 rows×8 lines, and 10 rows×8 lines.

[0011] Additionally, according to another aspect of the presentinvention, there is provided a manufacturing method for a connectorcomponent for optical fibers, the connector component including a basematerial made of quartz glass and provided with at least two holes forinserting and fixing optical fibers, the manufacturing method includingthe steps of: (a) arranging a plurality of inner components for formingholes for inserting optical fibers in a die for forming an outer form ofthe connector component with a dimensional accuracy equal to or lessthan 2 μm; (b) pouring slurry into the die, the slurry including quartzpowder, a resin binder, a dispersant, water and a curing agent; (c)curing the poured slurry; and (d) heating the cured slurry under vacuumso as to vitrify the cured slurry to obtain the quartz glass.

[0012] According to the above-mentioned aspect of the present invention,it is possible to manufacture the connector component for optical fiberswith high dimensional accuracy.

[0013] Additionally, according to another aspect of the presentinvention, the quartz glass may be high purity quartz glass containingequal to or more than 99.9% SiO₂, equal to or less than 10 ppm Al₂O₃,equal to or less than 1 ppm Li₂O, equal to or less than 10 ppm MgO,equal to or less than 10 ppm TiO₂, equal to or less than 10 ppm ZrO₂,equal to or less than 10 ppm K₂O, equal to or less than 10 ppm Na₂O,equal to or less than 10 ppm ZnO, equal to or less than 10 ppm CaO, andequal to or less than 10 ppm BaO. It is preferable that, by using theabove-mentioned high purity quartz glass, the thermal expansioncoefficient of the quartz glass of which the connector component is madeis controlled to be in a range of 0.45˜0.6×10⁻⁷/° C., and thetransmission rate of ultraviolet light having wavelength 356 nm iscontrolled to be equal to or more than 90%. It should be noted that theabove-mentioned high purity quartz glass may include another componentas long as the component thereof does not cause harm to the opticalcharacteristics of the high purity quartz glass.

[0014] Additionally, according to another aspect of the presentinvention, there is provided an optical member, including: opticalfibers; and a connector component for optical fibers, the connectorcomponent including a base material made of quartz glass and providedwith two or more holes for inserting and fixing the optical fiberstherein, wherein the connector component is fixed to ends of the opticalfibers by using epoxy thermosetting type adhesive or ultraviolet curingtype adhesive.

[0015] According to the above-mentioned aspect of the present invention,exposed strands of optical fibers are inserted into respectivecapillaries (holes), adhesive is filled in between the optical fibersand the capillaries, and a curing light is irradiated to the adhesive.Thereby, the adhesive is solidified and the optical fibers andcapillaries are fixed to each other. Since the irradiated light istransmitted in the capillaries, even when the outer side is covered withan armoring material, it is possible to irradiate the curing lightinside the capillaries from the ends of the capillaries. Further, thecapillaries and the exposed strands of the optical fibers are morepositively adhered and fixed to each other inside the capillaries by theadhesive solidified by the irradiated working light.

[0016] According to the above-mentioned aspects of the presentinvention, when the connector component for the optical fibers iscombined with optical fibers, the composition of the connector componentand the composition of the optical fibers are the same, and the thermalexpansion coefficient of the connector component and the thermalexpansion coefficient of the optical fibers are almost the same. Thus,stress to bonded parts does not increase since the stress is due tovariation in the size of the connector component and the optical fiberscaused by variation of environmental temperature. Accordingly,reliability of adhesion is higher.

[0017] The above-mentioned connector component may be more useful sincethe sizes of fiber arrays have been increasing recently. On the otherhand, the optical member and optical component using a ferrule made ofquartz and a fiber array made of quartz have advantages in that variouscharacteristics can be obtained almost the same as design targets inoptical designing. As for the various characteristics, there are thepolarized wave dependent property according to a wavelength plate,reduction in loss in AWG (arrayed waveguide grating), dispersionproperty and transmission distance of optical fibers, for example.

[0018] Additionally, the optical member combining the connectorcomponent and optical fibers uses light-curing resin as an adhesive. Atthe same time, in the optical member, capillaries are formed by using amaterial that can transmit working light. Thus, the adhesive is cured byirradiating the working light from the ends of the capillaries.Accordingly, besides the above-mentioned effects, the capillaries andthe optical fibers are fixed to each other.

[0019] Therefore, a terminal structure formed by combining the connectorcomponent and optical fibers does not need a burdensome process forsolidifying the adhesive, for example, stopping work on the terminalstructure for a required reaction time so that the adhesive issolidified and performing heat treatment on the terminal structure. Itis possible to simply manage the terminal treatment process of opticalfibers with a predetermined irradiating process. As a result, thebuilding process can be facilitated, efficiency can be improved, andmanufacturing cost can be reduced. Thus, the connector componentaccording to the present invention is suitable for quantity production.

[0020] Other objects, features and advantages of the present inventionwill become more apparent from the following detailed description whenread in conjunction with the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 is a perspective view of a conventional V-shaped groovearray;

[0022]FIG. 2A is a front view of a fiber array according to anembodiment of the present invention;

[0023]FIG. 2B is a longitudinal sectional view of the fiber array inFIG. 2A according to the embodiment of the present invention;

[0024]FIG. 3A is a front view of a ferrule according to anotherembodiment of the present invention;

[0025]FIG. 3B is a longitudinal sectional view of the ferrule in FIG. 3Aaccording to the embodiment of the present invention;

[0026]FIG. 3C is a rear view of the ferrule in FIG. 3A according to theembodiment of the present invention;

[0027]FIG. 4 is a schematic diagram showing the structure of a jumpercable using the fiber array shown in FIGS. 2A and 2B; and

[0028]FIG. 5 is a schematic diagram showing the structure of anotherjumper cable using the ferrule shown in FIGS. 3A, 3B and 3C.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] A description will be given of embodiments of the presentinvention, by referring to the drawings.

[0030]FIG. 2A is a front view of a fiber array 1 according to anembodiment of the present invention. FIG. 2B is a cross sectional viewof the fiber array 1.

[0031]FIG. 3A is a front view of a ferrule 11 according to anotherembodiment of the present invention. FIG. 3B is a cross sectional viewof the ferrule 11, and FIG. 3C is a rear view of the ferrule 11.

[0032] As shown in FIG. 2A, the fiber array 1 is formed by a prismaticbase material 3 having a plurality of fiber-insertion holes 5 therein.The fiber insertion holes 5 are arranged in a lattice state such as inan 8 rows×8 lines arrangement. Additionally, as shown in FIG. 2B, alledges of the fiber insertion holes on one side of the fiber array 1 arechamfered so as to form surfaces 5 a. In addition, as shown in FIG. 3A,the ferrule 11 is formed by a column-shaped base material 13 having aplurality of fiber insertion holes 15. The fiber insertion holes 15 arearranged in a 2×2 latticed state, for example. As shown in FIGS. 3B and3C, a cone-shaped hollow 13 a is formed on one end of the ferrule 11 sothat the hollow 13 a communicates with the fiber insertion holes 15.

[0033] Next, a description will be given of an optical member to whichthe connector component for optical fibers according to theabove-mentioned embodiments of the present invention is applied. Itshould be noted that in this specification, the word “connectorcomponent” refers to a fiber array and a ferrule, and the like

[0034]FIG. 4 is a schematic diagram showing the structure of a jumpercable 21 using the above-mentioned fiber array 1. FIG. 5 is a schematicdiagram showing the structure of another jumper cable 31 using theabove-mentioned ferrule 11.

[0035] As shown in FIG. 4, the jumper cable 21 is structured by usingthe fiber array 1 and optical cables 23. Additionally, as shown in FIG.5, the jumper cable 31 is structured by using the ferrule 11 and opticalfibers 33.

[0036] The connector components for optical fibers structured asmentioned above have the same material composition as optical fibers.Thus, thermal expansion coefficients of the connector components and athermal expansion coefficient of optical cables are almost the same.Accordingly, when the connector component is combined with the opticalfibers, higher reliability of adhesion is achieved since stresses tobonded parts do not increase. In this case, the stresses are caused byvariations of the sizes of the connector components and optical fibersaccording to the variation of environmental temperature.

[0037] In the following, a description will be given of an experimentperformed by the inventors of the present invention.

[0038] First, quartz powder (average particle diameter: 0.5 μm) of 99.9%purity was dispersed in alkaline solution with epoxy resin as an organicbinder and an organic dispersant. Thus obtained material was put througha sieve having 200 meshes, and a hardening agent was added thereto.Thereafter, the material was defoamed by agitation under vacuum so as toobtain slip (slurry). Then, the slip was poured into a die for formingthe outer form of the connector component for optical fibers. Twelveinner components for forming holes for inserting optical fibers werepreviously arranged in the die with a dimensional accuracy equal to orless than 2 μm. When the slip was cured, a formed material was obtained.The formed material was naturally dried for one night. Then, the formedmaterial was tentatively sintered for an hour at 850° C. Thereafter, theformed material was sintered under vacuum atmosphere (equal to or lessthan 10⁻² Torr).

[0039] Thus obtained sintered material was in a transparent andcolorless glass state (referred to as “high purity quartz glass”,hereinafter). The holes provided in the sintered material were polishedusing a PC wire and diamond slurry so as to form holes with apredetermined hole diameter. Then, the holes were cleaned and a desiredfiber array was obtained. Table 1 shows measured results of a distancebetween the holes for inserting the optical fibers of theabove-mentioned fiber array having 12 cores. As shown in Table 1, theholes were arranged with an accuracy of 250 μm±1 μm with respect to adesign target value of 250 μm. TABLE 1 sample distance between holes No.1-2 2-3 3-4 4-5 5-6 6-7 7-8 8-9 9-10 10-11 11-12 1 250.6 250.2 294.6249.1 250.3 250.9 249.1 250.6 250.4 249.5 250.5 2 250.1 250.3 250.9250.4 249.6 250.1 249.1 250.5 249.5 249.9 205.7 3 250.3 250.2 249.8249.6 250.3 250.8 249.6 249.7 249.3 250.9 250.4 4 250.1 249.8 249.6250.4 250.6 250.7 249.7 249.3 250.1 250.0 250.4 5 249.4 250.6 250.1250.3 250.0 249.7 249.9 250.6 250.1 250.2 250.7

[0040] Additionally, the thermal expansion coefficient of the obtainedfiber array was 0.52×10⁻⁶ /° C., which was almost the same thermalexpansion coefficient (0.5×10⁻⁶/° C.) of quartz glass that is thematerial of the optical fibers. Further, the fiber array had a 92%transmission rate of ultraviolet light having wavelength 356 nm.

[0041] An ultraviolet curing type adhesive was filled in the holes forinserting optical fibers of the fiber array made of glass. Thereafter,single-mode optical fibers were inserted in the respective holes. Theoptical fibers were fixed by irradiating ultraviolet light for 15minutes.

[0042] An SC type single-core ferrule was fixed on the other ends of thesingle-mode optical fibers by using a thermosetting adhesive. An opticalfiber cable (optical member) was obtained by optically polishing ends ofthe fiber array and the ends of the SC type single-core ferrule.

[0043] Thus obtained optical fiber cable was maintained for 2000 hoursunder an atmosphere of 85% humidity and 85 ° C. Then, adhesion strengthon the fiber array side was measured. As a result, adhesion strength notless than 12 N through 34 N was maintained. Thus, it was confirmed thatthe connector component according to the embodiment has high reliabilityin the adhesive characteristic.

[0044] In the optical member, it is preferable that polarized waveholding fibers are used for the optical fibers, so that an extinctionrate is equal to or greater than 25 dB.

[0045] Additionally, in the optical member, it is preferable that eachof the thermosetting type adhesive and the ultraviolet curing typeadhesive has equal to or less than 0.2 dB insertion loss, equal to ormore than 55 dB reflection loss, and equal to or more than 10 N tensilestrength.

[0046] The present invention is not limited to the specificallydisclosed embodiments, and variations and modifications may be madewithout departing from the scope of the present invention.

[0047] The present application is based on Japanese priority applicationNo. 2002-072710 filed on Mar. 15, 2002, the entire contents of which arehereby incorporated by reference.

What is claimed is:
 1. A connector component for optical fibers, saidconnector component comprising a base material provided with at leasttwo holes for inserting and fixing optical fibers therein, wherein saidbase material is made of quartz glass.
 2. The connector component foroptical fibers as claimed in claim 1, wherein the quartz glass is highpurity quartz glass containing equal to or more than 99.9% SiO₂, equalto or less than 10 ppm Al₂O₃, equal to or less than 1 ppm Li₂O, equal toor less than 10 ppm MgO, equal to or less than 10 ppm TiO₂, equal to orless than 10 ppm ZrO₂ equal to or less than 10 ppm K₂O, equal to or lessthan 10 ppm Na₂O, equal to or less than 10 ppm ZnO, equal to or lessthan 10 ppm CaO, and equal to or less than 10 ppm BaO.
 3. The connectorcomponent for optical fibers as claimed in claim 1, wherein a thermalexpansion coefficient of the quartz glass is within a range of0.45˜0.6×10⁻⁷/° C.
 4. The connector component for optical fibers asclaimed in claim 1, wherein the quartz glass has equal to or more than90% transmission rate for an ultraviolet light having a wavelength of356 nm.
 5. A manufacturing method for a connector component for opticalfibers, said connector component comprising a base material made ofquartz glass and provided with at least two holes for inserting andfixing optical fibers, said manufacturing method comprising the stepsof: (a) arranging a plurality of inner components for forming holes forinserting optical fibers in a die for forming an outer form of theconnector component with a dimensional accuracy equal to or less than 2μm; (b) pouring slurry into said die, said slurry including quartzpowder, a resin binder, a dispersant, water and a curing agent; (c)curing the poured slurry; and (d) heating the cured slurry under vacuumso as to vitrify the cured slurry to obtain the quartz glass.
 6. Anoptical member, comprising: optical fibers; and a connector componentfor optical fibers, said connector component including a base materialmade of quartz glass and provided with two or more holes for insertingand fixing the optical fibers, wherein said connector component is fixedto ends of the optical fibers using epoxy thermosetting type adhesive orultraviolet curing type adhesive.
 7. The optical member as claimed inclaim 6, wherein polarized wave holding fibers are used for the opticalfibers, so that an extinction rate is equal to or greater than 25 dB. 8.The optical member as claimed in claim 6, wherein each of thethermosetting type adhesive and the ultraviolet curing type adhesive hasequal to or less than 0.2 dB insertion loss, equal to or more than 55 dBreflection loss, and equal to or more than 10 N tensile strength.